// editor3
#include<stdio.h>
#include<string.h>
struct Node{
    int id;
    int arrival;
    struct Node* next;
};
struct Node* front = NULL;
struct Node* rear = NULL;
void enqueue(int id, int arrival){
    struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));
    newNode->id = id;
    newNode->arrival = arrival;
    newNode->next = NULL;
    if(rear == NULL){
        front = rear = newNode;
    }else{
        rear->next = newNode;
        rear = newNode;
    }
}
void dequeue(){
    if(front == NULL){
        return;
    
    struct Node* temp = front;
    printf("%d\n", temp->id);
    front = front->next;
    
    if(front == NULL)
        rear = NULL;
    free(temp);    
}
int main(){
    int n;
    scanf("%d",&n);
    if(n<=0){
        printf("Invalid input");
        return 0;
    }
    int id,arrival;
    for(int i=0;i<n;i++){
        scanf("%d %d", &id, &arrival);
        if(id <= 0 || arrival < 0){
            printf("Invalid input");
            return 0;
        }
        enqueue(id, arrival);
    }
    while(front != NULL){
        dequeue();
    }
    return 0;
}